one-point connectification

Money is one of the most important inventions of mankind. Just take a moment and appreciate the craziness of being able to express a full body massage in terms of wine glasses.

Mathematically speaking, money acts as the one-point connectification of the graph of tradable pairs of goods and services. (In the same spirit as the one-point compactification of a topological space.) Once it is introduced into an economy all goods and services can be converted to each other. In other words, by definition, there is nothing more liquid than money.